Crude oil is produced in many fields as a water in oil emulsion. It is desirable to separate or "break" the emulsion prior to transport and processing. To this end, various surface active or "surfactant" compositions have been developed and utilized over the course of many decades. Of these surfactant compositions that have found use as emulsion breakers, the most important are the alkylene oxide derivatives of phenolic resins.
An explanation of the synthesis, properties, and use of such resins can be found in the work of DeGroote et al. See, U.S. Pat. Nos. 2,524,890; 2,524,891; 2,524,892. DeGroote teaches the use as an oil emulsion breaker of ethoxylated derivatives of phenolic resins made by the condensation of formaldehyde, cardanol (a meta-substituted phenol derived from the shells of cashew nuts); and various ortho- and para-substituted phenols. This condensation may be either acid or base catalyzed, producing resins having at least 3 and up to 7 phenolic units, whose molecular weight increases by subjecting the reaction to vacuum distillation and heating conditions. DeGroote reports preparation of phenolic resins having up to 20 phenolic units, but expresses a preference and claims for emulsion breaking purposes resins having fewer than seven phenolic groups per molecule, prepared in an acid catalyzed condensation.
As noted by DeGroote, emulsion breakers can be introduced at various points along the chain of oil production. Typically, demulsification is conducted via heater treater vessels, in which the oil is separated in the presence of heat and emulsion breaker.
Various derivatives of phenolic resins have found use as emulsion breakers. Most commonly, the resins are oxyalkylated to increase their molecular weight and the hydrophilic/lypophlic balance. The cardanol resins may be sulfonated at the double bond in the unsaturated side chain moiety. The molecular weight of the emulsion breaker may also be increased by adding an unsaturated acid anhydride (such an maleic anhydride), followed by polymerization with, e.g., acrylic acid. The preparation and properties of such derivatives are likewise known in the art.
What I believe is not known in the art, for which I seek protection and exclusivity by these Letters Patent, is the preparation of phenolic resins (and their derivatives) having a higher molecular weight (8,000-40,000) with a branched structure and a higher number of phenolic moieties per molecule (40-100) than those known in the art, and the recognition that these phenolic resins exhibit unexpectedly superior performance characteristics when used as emulsion breakers.